1. Field of the Invention
This invention relates to the field of vehicular tonneau covers, specifically mechanisms for attaching and raising the covers.
2. Prior Art
Pickup trucks have become one of the most popular vehicles, with 3 million new pickups bought each year in the US. Until recently, they were primarily a utilitarian vehicle for farmers and tradesmen. Now pickups are customized with many accessories for recreational use and family use. One of the most popular accessories is a hard tonneau cover that enhances the appearance of the bed, improves fuel economy, and protects the bed contents from weather and from theft.
For many years, hard tonneau covers have been attached to the front of the vehicle bed with a hinge mechanism. At the rear of the cover, a latch or lock mechanism secures the cover in the lowered position. Gas springs attach to the cover and the inside of the bed near the rear of the cover to counteract the cover's weight so that less force is required to raise the rear of the cover and to hold the cover in the raised position.
A major problem with this common attachment system is that it limits access to cargo located at the front of the bed. A second major problem is that it limits the height of the contents of the bed, and prevents items such as large appliances or sofas from being transported without removal of the cover.
A number of inventors have tried to solve these two problems. U.S. Pat. No. 4,613,181 to Raf-Zadeh (1986) and U.S. Pat. No. 4,673,209 to Raf-Zadeh (1987) disclose a complex folding arm at each of 4 corners of a rigid tonneau cover. One deficiency of this invention is that the rear of the tonneau cover cannot be raised by itself, as is common practice with tonneau covers. In addition, easy one-person operation is not possible with described spring-assist mechanism. Another drawback is that the height is not adjustable. A further deficiency is that the mechanism presents insufficient longitudinal restraint to the cover when it is in the raised position and therefore would be dangerous during hard breaking or acceleration.
U.S. Pat. No. 5,988,728 to Lund et al. (1999) discloses a mechanism for hard tonneau covers comprised of side rails that permit cover support brackets to slide thus enabling the cover to slide rearward before the rear edge is raised. Shortcomings of this include that it cannot sufficiently raise the front of the cover to enable good access to cargo and its raised height is not easily adjustable. Furthermore, the disclosed rail-slider mechanism is prone to failure due to sand, dirt and ice or snow. Sealing between bed and cover is also not practical, allowing entry of rain, dirt and ice. The invention is limited in use to vehicles with tapered beds whose owners require hard tonneau cover that fits flush with the topside of the bed for aesthetic reasons.
U.S. Pat. No. 6,712,418 to Lathers (2004) discloses a modular cover assembly comprising rigid side panels, a center panel and support hardware. A significant problem is the tremendous tooling cost and stocking expense of a modular cover assembly that needs to be custom molded for a diverse automotive market which has many models and sizes. The forty two sheets of drawings illustrate the impractical complexity of the disclosed modular cover assembly and lifting mechanism, which often incorporates such costly design features as G-hinges.
The TopUp Corporation claims a U.S. Pat. No. 6,209,994 but discloses a mechanism requiring an electric/hydraulic motor. “X” members attach to the cover on each side of the bed and the rearward ends of the “X” members slide in tracks. A switch causes the electric/hydraulic system to raise the entire cover. The disclosed slider-track mechanism is prone to failure due to sand, dirt and ice or snow and even minor dents in tracks will prevent operation. In addition, the extended X members are inadequate to support the side loads of the hard tonneau cover when driving. All electric operated lift mechanisms face the following problems: the extra cost of an electric/hydraulic system, the extra cost to install and wire electric/hydraulic motor, the loss of cargo space in the bed due to mounting of electric motor/hydraulic pump and cylinders, and the inability to raise the cover due to electric motor/hydraulic pump failure or dead battery. Another problem is that access to cargo is much slower than with manual systems. Furthermore, the user can't raise just the rear of the cover for easy access to cargo.
U.S. Pat. No. 6,227,592 to Thacker and U.S. Pat. No. 6,666,490 to Thacker disclose other mechanisms requiring an electric/hydraulic motor. A front member on each side connects the front of the cover to a mid-point on the bed. A rear member on each side connects the rear of the bed to a mid-point on the cover. A rigid bow runs transversely under the cover to connect the two front members and a second rigid bow runs transversely under the cover to connect the two rear members. A powerful electric hydraulic pump is attached to one member and a switch causes the hydraulic system to raise the entire cover.
This invention is a heavy-duty system but has a number of drawbacks in addition to that of being quite expensive. As the cover is raised, the forward ends of the members move rearward. At maximum height, the cover overhangs the bed by approximately the length of the member, and the front of the bed is exposed an equal amount. And all electric operated lift mechanisms face the following problems: the extra cost of an electric or electric/hydraulic system, the extra cost to install and wire electric motors or hydraulic components, the loss of cargo space in the bed due to mounting of electric motor/hydraulic pump and cylinders, and the inability to raise the cover due to electric motor/hydraulic pump failure or dead battery. Access to cargo is also much slower than manual systems. Furthermore, the user can't raise just the rear of the cover for easy access. In addition the invention is not easily adaptable to the popular inexpensive fiberglass tonneau covers.
U.S. Pat. No. 6,149,220 to Weldy et al. discloses a mechanism comprised of a hinge-slider-lock mechanism at each of 4 corners of a lightweight tonneau cover. A rod is attached at each corner of the bed with its other end sliding in a channel on the bottom of the cover. In operation, the user unlocks both locks at the ends of either a side or the rear of the cover. Then the user manually lifts the chosen side of the lightweight cover. The rods slide to the corner of the cover to support it in the fully raised position.
Although the invention allows easier access to contents located at the front of the bed, it can not raise the entire cover to permit hauling tall cargo because one side must stay attached to the bed. Another problem is that the height of the raised side cannot be adjusted because the cover can only be supported in the fully raised position. Another drawback is the need to unlock two locks every time the cover is raised. Furthermore, the locks are vertically oriented so that lock covers are a practical necessity to prevent water and dirt from falling into the lock assembly and thereby preventing it use.
In addition, this invention can't be used to attach and raise a conventional hard fiberglass tonneau because this type of popular cover is too heavy for most people to manually lift. As noted previously, slider mechanisms are prone to failure due to sand, dirt and ice or snow and denting of the track.